Recently a routine DPS patrol parked outside a bar in Bandera, Texas. After last call the trooper noticed a man leaving the bar so intoxicated that he could barely walk. The man stumbled around the parking lot for a few minutes, with the trooper quietly observing.
After what seemed an eternity, and trying his keys on five different pickups, the man managed to find his own truck, which he collaspsed into. He sat there for a few minutes as a number of other patrons left the bar and drove off. Finally he started her up, switched the wipers on and off (it was a fine, dry summer night), flicked the blinkers on, then off a couple of times, honked the horn and then switched on the lights. He moved the vehicle forward a few inches, reversed a little and then remained still for a few more minutes as some more of the other patron vehicles left. At last, the parking lot empty, he pulled out of the parking lot and started to drive slowly down the road.

The trooper, having patiently waited all this time, now started up his car, put on the flashing lights, and promptly pulled the man over and carried out a breathalyzer test. To his amazement, the breathalyzer indicated no evidence of the man's having consumed any alcohol at all! Dumbfounded, the officer said, "I'll have to ask you to accompany me to the station. This breathalyzer must be broken."

"I doubt it," said the Texan. "Y'all see, tonight I'm the designated decoy."

Good one!